Even low levels of stress could cause infertility

It's a vicious circle of the cruellest kind. Stress might be causing infertility in women, according to new research. This could explain some cases in which couples are diagnosed as infertile with no apparent cause. Taking longer than usual to conceive can lead to stress, so the problem could become self-perpetuating.

A link between everyday life stresses and infertility has long been suspected, but there has been little hard evidence connecting the two. Women receiving fertility treatment are generally advised to avoid stress, but not so the average person trying to conceive. An estimated one in seven couples in the UK have fertility problems and, in about a quarter of those, there is no known medical explanation, and they are given a diagnosis of "unexplained infertility".

To explore the role of stress, Courtney Lynch at Ohio State University in Columbus and her colleagues collected saliva samples from 373 women in the US who had just started trying to conceive naturally and measured levels of an enzyme called alpha-amylase, a marker of stress.

Less sex?

After one year of regular unprotected sex, about 13 per cent of the couples had failed to get pregnant, the standard definition of infertility. The third of women who had the highest alpha-amylase levels were twice as likely to be in the infertile group as the third with the lowest levels.

In a previous study, Lynch's team found that those with higher levels of the stress enzyme were slightly less likely to conceive in their first month of trying. But this is the first time that alpha-amylase has been linked to clinical infertility.

But this study did not reveal what the mechanism might be. Nor did it investigate whether men's stress levels also have an effect. Melanie Davies of University College London Hospitals says it could have been through direct effects of stress on the body or simply because people who are stressed tend to have less sex.

Couples were asked to record when they had sex, and there was very little difference between those with the highest alpha-amylase levels and the lowest. But Davies says that people in such studies sometimes lie about how often they have sex.

Knowledge is power

Jacky Boivin at Cardiff University, UK, who has previously shown that stress does not affect fertility in couples undergoing IVF, warns that the latest findings might make people even more stressed. "There might be other things that the couple ought to focus on, like having more sex and not smoking," she says.

But Lynch disagrees. She thinks that the knowledge that stress could be behind some of the cases of unexplained infertility could help couples to take action.

"If you're having trouble getting pregnant and it's been around five to six months, it seems reasonable to suggest considering some sort of stress-reduction programme," she says. "Things like yoga, meditation or regular daily exercise have been shown to reduce stress. It's best to try to find something that fits into your lifestyle."

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